Effects of dispersal status on pituitary and gonadal function in the male spotted hyena

Male spotted hyenas (Crocuta crocuta) reach puberty at 24 months of age and then usually emigrate from their natal clans one to 52 months later. Recent work has shown that reproductive success is very low among adult males still residing in their natal groups, and it is similarly low among recent or "short-term" immigrants. Long-term immigrants father the vast majority of cubs born. Here we inquired whether these differences in reproductive success might be associated with variation among males in pituitary or gonadal function. In one free-living hyena population in Kenya, we compared baseline levels of plasma luteinizing hormone (LH) and testosterone (T) among adult natal males, short-term immigrants, and long-term immigrants, and we also compared their pituitary and gonadal responses to GnRH challenge. Mean basal plasma LH values did not differ among groups, but mean basal T concentrations in long-term immigrants were higher than those in either natal males or short-term immigrants. Similarly, pituitary response to GnRH challenge did not vary significantly among groups, but testicular response to challenge was greater in long-term immigrants than in natal males or short-term immigrants. Thus adult natal and immigrant males exhibited similar pituitary function but testicular function was attenuated among adult males that had not yet left their natal groups and also among males attempting to become established in new social groups. This suggests that, like the act of emigration itself, the process of social integration during immigration may have important physiological consequences for male mammals transferring between groups.     

Effects of repeated eastward and westward synchronizer phase-shifts on growth, blood morphology and biochemical variables in male domestic fowls

The effects of repeated synchronizer phase-shifts on growth (increment in body weight), blood morphology and growth related biochemical variables in 3-day-old juvenile male chicks were evaluated till they become 20 weeks old. The control birds were kept under a fixed LD 12:12 light schedule throughout, while the LD 12:12 regimen of experimental birds was shifted weekly either by delaying (westward shift) or by advancing (eastward shift) the time of light onset by 8 hr. The rate of growth was more in fowls which were exposed to repeated advancement of synchronizer schedule than the controls and those exposed to westward shifts of the synchronizer schedule. Hematological indices, viz., hemoglobin concentration, number of circulating erythrocytes, hematocrit and biochemical variables, such as concentration of glucose and protein in plasma; glycogen, protein and lipid in liver; and muscle tissues were significantly more in chicks exposed to repeated eastward shifts, when compared with the control birds (LD 12:12). It is suggested that the eastward shift of the synchronizer may be beneficial for the poultry birds.     

Spatial organization in flocks of domestic fowls

The movements of individual birds within flocks were recorded by marking a sample with coloured tags and photographing the flock at fixed intervals using eight time-lapse cine, cameras, each camera covering a field amounting to one-eighth of the total area. The birds were housed on deep litter in an area 13·4×5·2 m, and flock sizes of four to 600 were used they ranged in age from 9 weeks to adult. The films were analysed, the positions of the marked birds were plotted and the probability of the observed distributions occurring by chance were calculated. Previous workers have found that individual birds move over, only part of the total area; in our study the movements of individuals lay on a continuum ranging from apparent randomness at one extreme to clear non-randomness at the other. Moreover, in all experiments most birds were sighted in most camera fields, indicating that their movements were incompatible with the accepted definition of a delineated home range. These results were explained by postulating strain differences in aggressiveness and assigning an important role to illumination level. At very low light levels individuals may be able to move freely in a flock because they cannot be recognized as strangers and, in any case, individual recognition may be exceptional in large flocks. Even so, birds did differ in the extent to which they moved around and some did exhibit preferences for particular parts of the pen; such tendencies were consistent over a 4-week period in adults but not in juveniles.     

Effects of 1800 MHz GSM-like exposure on the gonadal function and hematological parameters of male mice

The aim of this study was to evaluate the possible effects of in vivo 1800 MHz GSM-like exposure on male reproduction. In five separate experiments, male NMRI mice (35-41 g) were exposed (11-12 mice each) to 1800 MHz GSM-like radiation. The average power density was 100 microW/cm2, the estimated SAR was 0.018-0.023 W/kg. The animals were exposed ten times (over two weeks on workdays) and the duration of exposure was 2 h/day. On the day of the last treatment, mice were anesthetized with i.p. pentobarbital, and blood samples were taken for hematology, serum chemistry and serum testosterone (T) determinations (ELISA). Testicles, epididymes, adrenals, prostates and pituitary glands were removed for histology. One testicle of each animal was used for culture of Leydig cells. The cells were cultured for 48 h in the presence or absence of human chorionic gonadotropin (hCG) to evaluate the in vitro steroidogenic response of Leydig cells. In the exposed animals red blood cell count (RBC: 8.59+/-0.10 T/l, n=37) and volume of packed red cells (VPRC: 42.29+/-0.43%, n=37) were significantly higher (p<0.01) compared with the controls (RBC: 8.12+/-0.08 T/l, n=36; VPRC: 39.76+/-0.36%, n=36). The serum testosterone level of the exposed animals (7.85+/-1.08 ng/ml, n=56) was also significantly elevated (p<0.05) compared to the controls (5.12+/-0.79, n=52), while the in vitro steroidogenic capacity of the Leydig cells was unaltered. No significant differences in the other investigated variables were found between controls and exposed mice. Our results indicate that the applied GSM-like microwave exposure may induce slight, but statistically significant alterations in some hematological and endocrine parameters of male mice within the physiological range. Further investigations are required to establish the biological significance of these phenomena.     

Effects of aproteic diet on hypothalamic-pituitary- gonadal regulation in the male rat

The effect of an aproteic diet (Ap) on the reproductive axis in young male rats was studied. Also the refeeding effect at different times after the aproteic diet was studied. The Ap diet was given during 21 days. In refeeding groups, the control diet was given during 2, 4 and 6 weeks after the aproteic diet. We studied the plasmatic testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels. Also the hypothalamic GnRH concentration and in vitro hypothalamic GnRH secretion in basal and induced condition was studied. The total protein deficit produced significant reduction in body, testis, seminal vesicles and prostate weights. This was accompanied with decreased levels of plasmatic testosterone (P<0.02). In this aproteic group there was a significant reduction in LH (P<0.05) and FSH (P<0.05) plasmatic levels. Refeeding with control diet reversed this situation, producing significant increment in LH (P<0.05) and FSH levels (P<0.01) at the fourth and second weeks, respectively. The basal hypothalamic GnRH secretion did not differ from the control; nevertheless the induced secretion was significantly (P<0.05) greater in the aproteic group. Also the hypothalamic GnRH concentration was increased (P<0.05) in animals fed with the aproteic diet. The minor testis, prostate, and seminal vesicles" weight, and a decreased plasmatic testosterone in rats fed with an aproteic diet, are produced by a decrease in gonadotrophin secretion. This decrease in turn is caused by a reduction in GnRH secretion, since hypothalamic GnRH concentration is increased in rats fed with the aproteic group, and induced secretion is greater in this group. All these alterations produced by an aproteic diet are reversible, since-with contol diet refeeding-the gonadotrophin secretion returned at control levels.     

Toxic effects of ingested lead shots in domestic fowls

Lead poisoning from ingested shots is thought to be a major cause of high mortality in waterfowls throughout the world, and some millions of fowls die each year. However, there have been no other Japanese studies regarding lead toxicity in birds from ingested lead shots. We used domestic fowls instead of waterfowls as the experimental birds, in order to make clear the distribution and the toxic effects of lead shot in the birds. In a 1-wk follow-up study, two, four, and eight #4 lead shots were administered orally. A dose-dependent increase of the lead concentrations in blood, brain, liver, kidney, lung, spleen, bone, and epidermis of the gizzard was observed. In the 12-wk follow-up study, twenty domestic fowls were used and eight #4 lead shots were administered to the experimental birds. Lead concentrations in brain, liver, kidney, bone, ovary, fat tissue, and breast muscle increased more than in the 1-wk follow-up study. The observed lead concentrations of organs in the domestic fowls were lower than those of the other species used in past studies. The blood lead concentrations increased up to the third week and a remarkable suppression of delta-aminolevulinic acid dehydratase activity in red blood cells and elevation of free erythropoietic protoporphyrin were observed in the exposed group. Body weight loss, loss of hair, and neurological symptoms were also observed. However, there were no mortalities during the 1- and 12-wk studies.     

Pituitary and gonadal function during physical exercise in the male rat

The effects of training and acute exercise on serum testosterone, luteinizing hormone (LH) and corticosterone levels and on testicular endocrine function in male rats were studied. In the first part of the study, the rats were trained progressively on a treadmill, over 8 weeks. Training did not change the basal levels of serum testosterone, LH and corticosterone, or the testicular concentrations of testosterone and its precursors progesterone and androstenedione. The levels of testicular LH (30.3 +/- 2.6 ng/g wet wt, mean +/- SEM) and lactogen (150 +/- 14 pg/g) receptors were unchanged after training. However, the capacity of testicular interstitial cell suspensions to produce cAMP and testosterone increased by 20-30% during in vitro gonadotropin stimulation. In the second part, the trained and untrained control animals underwent acute exhaustive exercise. Serum testosterone levels decreased by 74 and 42% in trained and untrained rats, respectively (P less than 0.02), and corticosterone rose by 182% in trained and 146% in untrained rats (P less than 0.01), whereas the LH level was unchanged. Testicular levels of testosterone and its precursors decreased, with the exception of unchanged androstenedione, in trained rats; the cAMP concentration was unchanged. In both trained and untrained rats, acute exercise decreased the capacity of interstitial cell suspensions to produce cAMP, whereas there were no consistent effects on testosterone production. Acute exercise had no effect on LH or lactogen receptors in testis tissue. In conclusion, training had no effect on serum or testicular androgen concentrations, but increased Leydig cell capacity to produce testosterone and cAMP. Acute exercise decreased serum and testicular testosterone concentrations without affecting serum LH. A direct inhibitory effect of the increased serum corticosterone level on the hypothalamic-pituitary level and/or testis may be the explanation for this finding.     

Analysis of genetic diversity and phylogenetic relationships among red jungle fowls and Chinese domestic fowls

Genetic diversity and phylogenetic relationships among 568 individuals of two red jungle fowl subspe- cies (Gallus gallus spadiceus in China and Gallus gallus gallus in Thailand) and 14 Chinese domestic chicken breeds were evaluated with 29 microstaellite loci, the genetic variability within population and genetic differentiation among population were estimated, and then genetic diversity and phylogenetic relationships were analyzed among red jungle fowls and Chinese domestic fowls. A total of 286 alleles were detected in 16 population with 29 microsatellite markers and the average number of the alleles observed in 29 microsatellite loci was 9.86±6.36. The overall expected heterozygosity of all population was 0.6708±0.0251, and the number of population deviated from Hardy-Weinberg equilibrium per locus ranged from 0 to 7. In the whole population, the average of genetic differentiation among population, measured as FST value, was 16.7% (P<0.001), and all loci contributed significantly (P<0.001) to this differentiation. It can also be seen that the deficit of heterozygotes was very high (0.015) (P<0.01). Reynolds' distance values varied between 0.036 (Xiaoshan chicken-Luyuan chicken pair) and 0.330 (G. gallus gallus-Gushi chicken pair). The Nm value ranged from 0.533 (between G. gallus gallus and Gushi chicken) to 5.833 (between Xiaoshan chicken and Luyuan chicken). An unrooted consensus tree was constructed using the neighbour-joining method and the Reynolds' genetic distance. The heavy-body sized chicken breeds, Luyuan chicken, Xiaoshan chicken, Beijing Fatty chicken, Henan Game chicken, Huainan Partridge and Langshan chicken formed one branch, and it had a close genetic relationship between Xiaoshan chicken-Luyuan chicken pair and Chahua chicken-Tibetan chicken pair. Chahua chicken and Tibetan chicken had closer genetic relationship with these two subspecies of red jungle fowl than other domestic chicken breeds. G. gallus spadiceus showed closer phylogenetic relationship with Chinese domestic chicken breeds than G. gallus gallus. All 29 microstaellite loci in this study showed high levels of polymorphism and significant genetic differentiation was observed among two subspecies of red jungle fowl and 14 Chinese domestic chicken breeds. The evolutional dendrogram is as follows: evolutional breeds→primitive breeds (Chahua chicken and Tibetan)→red jungle fowl in China (G. gallus spadiceus)→red jungle fowl in Thailand (G. gallus gallus). The results supported the theory that the domestic fowls might originate from different subspecies of red jungle fowl and Chinese domestic fowls had independent origin.     

Effects of exogenous gonadotropic and steroid hormones on the social behaviour and gonadal maturation of male domestic ducklings Anas platyrhynchos L.

Male domestic ducklings were injected during their first month of life with mammalian gonadotrophins (ovine LH or FSH, HMG) or gonadal steroids (testosterone or oestradiol). LH and testosterone stimulated sexual behaviour while oestradiol inhibited the increase of aggression observed in control birds during the experiment. The mammalian gonadotrophins did not increase plasma testosterone but nevertheless they all stimulated the testis growth. Several hypotheses which could explain this finding (stimulation of spermatogenesis without any apparent effect on testosterone) are discussed and the possibility of a direct action of LH on the sexual behaviour is analysed. Social displays were only moderately stimulated by testosterone and not at all by gonadotrophins. The hormonal controls of these behaviour patterns remains thus largely unknown.     

Age related modulation of circadian time structure of blood, plasma and tissue variables in male domestic fowls.

To study modulation of circadian time structure of 11 blood, plasma and tissue variables in male domestic fowls, as a function of age, three experiments were made in one-day-old fowls (72) standardized by 12L:12D. In the first experiment, at 6 week age, 24 birds were killed by decapitation, four each at six different circadian stages (2, 6, 10, 14, 18 and 22 hr after light onset, HALO). Equal number of birds were killed at similar circadian stages at the age of 12 and 18 week in the second and the third experiments, respectively. Age affected both, the circadian patterns and the mesors (24 hr mean values). The circadian pattern included amplitude (half of the total extent of variation) and acrophase (estimated time of peak) for each variable. The results clearly suggest that the pattern of circadian rhythm may vary as a function of age of the bird.     

Feeding behaviour in a population of domestic fowls in the wild

In 1976 the diet of adult feral fowls on a Scottish island consisted mainly of grass from January to July and oats from August to December. Juveniles ate many invertebrates in their first two months of life, but otherwise their diet was similar to that of the adults. In contrast to the non-breeding adults, broods and their dams showed two distinct types of feeding behaviour, called “sporadic” and “intensive” feeding. These were directed towards scattered and concentrated food sources, and the type shown depended mainly on the dam's behaviour. The significance of these and other aspects of feeding behaviour is discussed.     

An increase in activity of domestic fowls produced by nutritional deficiency

The effect of two specific nutritional deficiencies upon activity in chickens was investigated. Groups of pullets deprived of calcium in large cages showed significant increases in spontaneous activity; both as measured by complete body movements and also as pecking activity. Deprived birds, but not controls, were observed engaging in an aberrant behaviour pattern, ‘air pecking’. When the response of birds to various stimulus objects in an arena was tested, calcium deprivation resulted in significantly increased pecking activity, but it was not preferentially directed towards a potential calcium source and the pattern of pecking was similar to that observed in the controls. It did not prove possible to relate this increased activity to raised parathyroid hormone levels, and the fact that a similar increase in activity was seen under sodium deprivation suggests that the phenomenon may be of more general occurrence.     

Lack of spontaneous alternation in favor of perseveration in domestic fowls and pigeons

When allowed successive free choices of the arms of a T-maze, domestic fowls and pigeons repeated rather than alternated entries of the two alternatives. Such perseveration was less when one arm was black and the other white than when both were grey. Perseveration increased between the beginning and the end of the experiment and was unaffected by confinement to a chosen arm for 30 or 60 seconds. Removal from a chosen arm may have provided relief from an aversive situation and thus reinforced subsequent re-entries of the same arm. The results were therefore accounted for by the adoption of a win-stay escape strategy.